Investigators are searching for a second suspect in a triple murder in New Castle, according to the Lawrence County district attorney. Police have already arrested 19-year-old Stephen Procopio, of New Wilmington, and they plan to charge him with three counts of criminal homicide. A mother, her daughter and a man were all found dead inside a home on West North Street around 4:30 a.m. Tuesday. Investigators have learned that the 10-year-old girl was shot coming down the steps. Lawrence County District Attorney Josh Lamancusa said Procopio has been providing crucial information. When officers arrived at the home, they found Nichole Pumphrey, 31; her daughter, Amariah Emery, 10; and Lawrence Cannon, 30, dead on the first floor. Police say Pumphrey and her daughter lived at the home and Cannon lived elsewhere. A woman is also being held in police custody, although her connection to this case is unclear at this time.